More particularly the invention relates to a burner for a gas turbine engine comprising: a radial swirler for creating a swirling fuel/air mix; a combustion chamber in which takes place combustion of the swirling fuel/air mix; and a pre-chamber located between the radial swirler and the combustion chamber, the radial swirler comprising a plurality of vanes arranged in a circle, generally radially inwardly extending flow slots being defined between adjacent vanes in the circle, each flow slot having a radially outer inlet end, a radially inner outlet end, first and second generally radially inwardly extending sides provided by adjacent vanes, and a base and top, in use of the burner fuel and air travelling along the flow slots from their inlet ends to their outlet ends so as to create adjacent the outlet ends the swirling fuel/air mix, a flow slot comprising a first gas fuel injection hole in its base and a flow slot comprising a second gas fuel injection hole in its first side.
A burner of this type is known wherein there is a first gas fuel injection hole in the base of every flow slot and two second gas fuel injection holes in the first side of every flow slot. In this known burner all the first and second gas fuel injection holes are supplied by one and the same gas fuel supply gallery of a gas fuel supply manifold.
It is desired to reduce the nitrogen oxides (NOx) and carbon monoxide (CO) emissions of this known burner.